Manufacturing Process of a Wheel Nut Wrench

ABSTRACT

In order to provide a manufacturing process for a wheel nut wrench in which strength of a nut socket portion is increased even though the process is facilitated under a situation where a tube made of carbon steel such as S45C is used as a material, the process includes the steps of: using a tube-shaped steel tube, forming a nut socket shell portion having a cross section of a hexagonal shape at an end portion thereof by cold pressing, pressing a sleeve made by a belt-shaped steel plate being bent and having a cross section of a hexagonal shape into the nut socket shell portion, and unifying a nut socket portion with the sleeve by plastic deforming.

CROSS-REFERENCE TO THE RELATED APPLICATION

This is a divisional of application Ser. No. 12/640,169 filed Dec. 17,2009 which is incorporated here by reference, and which claimed priorityon Japanese Patent Application No. 2009-162246 filed Jul. 8, 2009, whichclaim is repeated here.

FIELD OF THE INVENTION

The present invention relates to a manufacturing process for a wheel nutwrench suitable to be used for attaching/detaching wheels of a vehicle.

BACKGROUND ART

As for a wheel nut wrench, there are various types of wheel nut wrenchessuch as an open-ended type, a single-ended T shape, and a single-ended Lshape. Among them, the single-ended L-shaped wheel nut wrench isconstituted in a manner that a round bar (an inner filling body) made ofcarbon steel is used in general, a nut socket portion is formed at a tipthereof by hot forging, and then a side where this nut socket portion isprovided is bent to an L shape. Among various types of wrenches such asthis single-ended L-shaped wheel nut wrench, there is one sold as asingle component, but most of them are each mounted in a vehicle as anaccessory attached to the vehicle. Thus, the number of wrenches isenormous, and a significant cost reduction is required.

Thus, as for the single-ended L-shaped wheel nut wrench in particular,in contrast with a conventional wheel nut wrench made after a round baris processed, a wheel nut wrench constituted in a manner that a nutsocket portion is formed by cold forging with a tube made of carbonsteel as a material, and a side where this nut socket portion isprovided is bent to an L shape is well known in Japanese PatentPublication No. Hei 3-27297, Patent Document 1.

As for the conventionally well-known wheel nut wrench disclosed inabove-described Patent Document 1, the material is a tube made of carbonsteel of S45C, and furthermore the nut socket portion can be formed bycold forging, and therefore it makes it possible to reduce amanufacturing cost compared to the conventional wheel nut wrench withthe round bar. However, in order to prevent that a thickness of the nutsocket portion thins to thereby reduce strength, a process to make thenut socket portion thick is required, and it takes time for this processto be performed, so that a problem that a sufficient cost reductioncannot be achieved is caused.

The wheel nut wrench, in actual use, is used in such a way that a handleportion is hit with a hammer, a supporting tube is inserted into ahandle portion, a foot or feet is/are put on a handle portion to apply atotal body weight thereon, or the like, and thus, there is often a casethat significant torsional pressure is applied on the nut socketportion.

Therefore, in the case when the single-ended L-shaped wheel nut wrenchis manufactured with a tube, how deformation-resistant strength againsttorsional pressure on the nut socket portion is increased under asituation where processes are made as easy as possible is a next issue.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a manufacturing processfor a wheel nut wrench in which strength of a nut socket portion isallowed to be increased even though a tube made of carbon steel is usedas a material and processes are facilitated.

In order to achieve the above-described issue, the present inventioncomprising the steps of, using a tube-shaped steel tube, forming a nutsocket shell portion having a cross section of a hexagonal shape at anend portion thereof by cold pressing, pressing a sleeve made by abelt-shaped steel plate being bent and having a cross section of ahexagonal shape into the nut socket shell portion, and unifying a nutsocket portion with the sleeve by plastic deforming.

The manufacturing process of the wheel nut wrench according to theclaims, wherein a shape of the nut socket shell portion is constitutedin a manner that outer and inner peripheries thereof are both formed ina hexagonal shape.

The present invention is further characterized in that a heat treatmentis performed for the sleeve.

The present invention is constituted as above, so that the followingeffects can be obtained.

A tube-shaped steel tube is used to form a handle portion, a bentportion, and a nut socket shell portion by cold pressing, and a sleevethat has a cross section of a hexagonal shape and is made of a steelplate similarly is pressed into the nut socket shell portion, and then aunification process is performed for the nut socket shell portion andthe sleeve, and thereby unification of both the nut socket shell portionand the sleeve is achieved, resulting that a process of the nut socketshell portion becomes easy to be performed in particular. Consequently,it becomes possible to provide a manufacturing process for a wheel nutwrench in which a nut socket portion is strengthened by the sleeve undera situation where a tube-shaped steel tube allowed to be manufacturedinexpensively is used.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a wheel nut wrench which is manufacturedaccording to the present invention;

FIG. 2 is a bottom view of the wheel nut wrench shown in FIG. 1;

FIG. 3 is a vertical cross-sectional view of the wheel nut wrench whichis manufactured according to the present invention;

FIG. 4 is a cross sectional view of the wheel nut wrench which ismanufactured according to the present invention when it is seen from adirection of an A-A line in FIG. 1;

FIG. 5 is a cross sectional view of the wheel nut wrench which ismanufactured according to the present invention when it is seen from adirection of a B-B line in FIG. 1;

FIG. 6 is a perspective view of a sleeve in the wheel nut wrench whichis manufactured according to the present invention;

FIG. 7 is a perspective view showing another embodiment of the sleeve inthe wheel nut wrench which is manufactured according to the presentinvention;

FIG. 8 is a perspective view showing another embodiment of the sleeve inthe wheel nut wrench which is manufactured according to the presentinvention;

FIG. 9 is a perspective view showing another embodiment of the sleeve inthe wheel nut wrench which is manufactured according to the presentinvention;

FIG. 10(1) to FIG. 10(4) are explanatory views showing a manufacturingprocess of a wheel nut wrench according to the present invention;

FIG. 11 is an explanatory view showing a forming process of a nut socketshell portion in the wheel nut wrench according to the presentinvention;

FIG. 12(1) to FIG. 12(4) are explanatory views to explain themanufacturing process of the wheel nut wrench according to the presentinvention; and

FIG. 13( a) and FIG. 13( b) show a case when a single-ended L-shapedwheel nut wrench is used as a handle for a rotary shaft of a vehiclejack, and FIG. 13( a) is an explanatory view thereof and FIG. 13( b) isa partial enlarged cross sectional view of the explanatory view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment to implement the present invention is a manufacturingprocess for a wheel nut wrench made with a tube-shaped steel tube andprovided with a nut socket portion at at least one end, a nut socketshell portion whose inner and outer peripheries are both formed in ahexagonal shape is provided at an end portion of the steel tube, asleeve made of a steel plate and having a cross section of a hexagonalshape is pressed into this nut socket shell portion, and a portion ofthe nut socket shell portion is deformed toward the sleeve to therebyachieve unification of the nut socket portion and the sleeve.

Hereinafter, an embodiment of the present invention will be explained indetail based on the drawings in the case when the present invention isapplied to a single-ended L-shaped wheel nut wrench, but the presentinvention can also be applied to an open-ended type wheel nut wrench anda T-shaped wheel nut wrench as it is besides the above.

FIG. 1 to FIG. 6 show one embodiment of a wheel nut wrench 1 which ismanufactured according to the present invention. According to thedrawings, the wheel nut wrench 1 according this embodiment is asingle-ended L-shaped wheel nut wrench, and is made of a tube-shapedcarbon steel tube, (which is also called a steel tube in the presentapplication), such as tube-shaped S45C, for example. This single-endedL-shaped wheel wrench 1 is constituted by a handle portion 2 having apierced hole 2 a, a bent portion 3 provided on one side end portion sideof this handle portion 2, and a nut socket portion 5 tube-expanded via ahead portion 4 provided at a tip of this bent portion 3, and the nutsocket portion 5 is constituted by a nut socket shell portion 5 a and asleeve 7 inserted into and fixed to this nut socket shell portion. Thissingle-ended L-shaped wheel nut wrench 1 is constituted by processing atube-shaped material, and thus a communication hole 6 is formed throughfrom the nut socket portion 5 to the handle portion 2. Further, in thissingle-ended L-shaped wheel nut wrench 1, a material thereof is a carbonsteel tube as described above, but besides the above, stainless steel(SUS) or aluminum alloy can be used. The pierced hole 2 a is formed in amanner that it is in a substantially elliptical shape and as for sizeson an entry 2 b side and an exit 2 c side, the entry 2 b side is largeand the exit 2 c side is small. However, the present invention is notlimited to the above.

As shown in FIG. 2 in particular, the handle portion 2, the bent portion3, the head portion 4, and the nut socket shell portion 5 a of the nutsocket portion 5 are substantially uniform in thickness, and inparticular, a thick portion is not formed. Thus, there is no need toform a thick portion by a tube shrinking process or an ironing process.Therefore, steps of a process are reduced and the process isfacilitated, and a tube expanding deformation process can be performedwithout exerting unreasonable force on the steel tube.

As for a shape of the nut socket shell portion 5 a as well, inner andouter peripheries both have a cross section of a hexagonal shape, inwhich a thickness between the inner and outer peripheries issubstantially the same as those of other portions, and the sleeve 7 thathas a cross section of a hexagonal shape and has the thickness same asthat of the nut socket shell portion 5 a similarly is pressed into andfixed to the inside. However, the nut socket shell portion 5 a istube-expanded from a tube diameter of the handle portion 2, andtherefore, the thickness is slightly thinner than those of the otherportions in the strict sense, but a thickness to be reduced is about 0.5mm, and there is no significant difference from the other portions.However, since the sleeve 7 is inserted into and fixed to this nutsocket shell portion 5 a, as the nut socket portion 5, the totalthickness is thicker than those of the handle portion 2, the bentportion 3, and the like besides the above.

This sleeve 7 is formed in a manner that a belt-shaped carbon steelplate made of, for example, S45C, (which is also called a steel plate inthe present application), is bent to have a cross section of a hexagonalshape, and as shown in FIG. 6 in particular, a joint 7 a is formed inone of flat plate portions 7 b. As for this joint 7 a, a joint whoseboth ends are simply abutted and a joint whose both ends are weldedtogether can be considered, and sufficient strength can be obtained byonly abutting. A material for this sleeve 7 is also S45C in thisembodiment, but stainless steel (SUS) can also be used.

Further, in respective corner portions 7 d and one of the flat plateportions 7 d of the sleeve 7, as shown in FIG. 5 and FIG. 6 inparticular, fixing holes 7 c are provided. As shown in FIG. 4, after thesleeve 7 is pressed into the nut socket shell portion 5 a, a portioncorresponding to each of corner portions 5 b of the nut socket shellportion 5 a and each of the fixing holes 7 c of the flat plate portions7 b is punched from the outside by using a punch, and the inside of thenut socket shell portion 5 a is bulged to the fixing holes 7 c to beengaged to the fixing holes 7 c, and thereby unification of the sleeve 7and the nut socket shell portion 5 a is achieved. In the drawing,concave portions made by punching are denoted by a reference numeral 5c.

This fixing hole 7 c, as shown in FIG. 5 and FIG. 6 in particular, isprovided in each of the corner portions 7 d and one of the flat plateportions 7 b of the sleeve 7, but the present invention is not limitedto these positions. Accordingly, in the present application, therespective corner portions 7 d and the flat plate portions 7 d are alsocalled a peripheral wall altogether. Further, the number of the fixingholes 7 c is not limited in particular, but there is a need to providethe fixing holes 7 c plurally. In the case when the fixing hole 7 c isprovided in the flat plate portion 7 b, it may be possible to omitproviding the fixing hole in one or two of the corner portions 7 dadjacent to the flat plate portion 7 b.

FIG. 7 shows another embodiment of the sleeve. According to the drawing,a sleeve 10 according to this embodiment is constituted in a manner thata formation of a joint 10 a is a jagged pattern.

This embodiment constituted in this manner makes it possible toeffectively prevent the sleeve 10 from twisting toward an axis directioneven when a strong torque is exerted on the nut socket portion of thewheel nut wrench in loosening or tightening a wheel nut. The jaggedpattern of the joint 10 a of this sleeve 10 may be zigzag, or as is asleeve 11 shown in FIG. 8, it may be constituted to have a joint 11 ahaving a crank shape.

FIG. 9 shows still another embodiment of the sleeve. According to thedrawing, fixing holes 12 a provided in a sleeve 12 are all provided incorner portions 12 b.

Even when this embodiment is constituted in this manner, an object ofthe present invention can be achieved, and this embodiment has anadvantage that it is possible to prevent that by punching, flat plateportions 12 c of the sleeve 12 are distorted inwardly to be deformed.Note that a reference numeral 12 d denotes a joint.

FIG. 10(1) to FIG. 10(4) through FIG. 12(1) to FIG. 12(4) show oneembodiment of a manufacturing process of a wheel nut wrench according tothe present invention.

First, as shown in FIG. 10(1), a carbon steel tube having a tubediameter of 19 m/m and a thickness of 2 m/m is cut in an appropriatelength to be formed as a blank tube A, and deburring or the like isperformed. Next, a side where the nut socket portion is provided, beingone end portion of the blank tube A, is placed in a beveling die in apress machine, which is not shown, and by using a not-shown punch bar,as shown in FIG. 10(2), a first tube expansion is performed to obtain afirst processed product B. Next, as for the first processed product Bmade after this first tube expansion is performed, a portion of thefirst processed product B, where the tube expansion is performed, isplaced in another beveling die that is not shown and whose insidediameter is further expanded, and by using a not-shown punch bar whosediameter is larger than that of the punch bar used in the first tubeexpansion, a second tube expansion is performed as shown in FIG. 10(3)to obtain a second processed product C. Next, a portion of this secondprocessed product C, where the tube expansion is performed, as shown inFIG. 11, is placed in a beveling die 13 provided with a hexagonal shapedhole in a plane, and by using a punch bar 14 having a cross section of ahexagonal shape similarly, as shown in FIG. 10(4), the portion is formedin a hexagonal shape in a plane to obtain a third processed product Dhaving a nut socket shell portion 15. At this time, a thickness of theportion where the nut socket shell portion 15 in a hexagonal shape in aplane is formed is uniform as shown in FIG. 5 and FIG. 6, but it ispossible to make the thickness of the portion thicker or thinner thanthose of other portions of the blank tube depending on the way how thenut socket shell portion 15 is formed. When the thickness is made thick,strength thereof is increased, and this portion is correlative tostrength of a later-described sleeve. The formation of the nut socketshell portion 15 in the blank tube A as above is performed by coldpressing. Note that the tube diameter and thickness of the blank tube Aare not limited to the above.

When the nut socket shell portion 15 in a hexagonal shape in a planecross section is formed at the one end portion of the blank tube A bytube expansion according to the above manner, as shown in FIG. 12( a),the step of pressing a sleeve 16 in a hexagonal shape in a plane that isformed at other steps into the nut socket shell portion 15 is started.Here, formation of the sleeve 16 is explained. The sleeve 16 is formedin a manner that a coiled carbon steel plate made of, for example, S45Cand having a thickness of 2 mm and a width of 20 mm is used, and thecarbon steel plate is cut while fixing holes 16 a are being punchedthrough by a not-shown progressive press machine and the carbon steelplate is being bent to a hexagonal shape in a plane (this hexagonalshape is adjusted to a shape of an outside diameter of a wheel nut). Atthis time, a joint 16 b is made, but it is preferable that this joint 16b is provided with a slight opening, (which is about 0.1 to 0.5 mm). Thethickness of the sleeve 16 is 2 mm in accordance with the thickness ofthe blank tube, but this thickness is not limited.

Further, the opening in the joint 16 b is an opening that is eliminatedbecause the entire sleeve 16 shrinks when the sleeve 16 is pressed intothe nut socket shell portion 15. A shape of the joint 16 b is straightin this embodiment, but it is arbitrary that the shape thereof is set asa zigzag shape, a clank shape, or the like. When a zigzag shape isapplied, there is an effect that it is possible to prevent that thesleeve 16 is twisted by torsional pressure, thereby a position of thesleeve 16 being displaced in an up and down direction when a wheel nutis tightened or loosened. The joint 16 b is preferably in a flat plateportion of the sleeve 16, but it is also possible to bring the joint 16b to a corner portion. Further, although an increase in cost is caused alittle, it is also possible to weld the joint 16 b. As for welding,continuous welding, spot welding, or the like is available.

The steps until the sleeve 16 in a hexagonal shape in a plane is formedare a cold press process, and it is preferable that a heat treatmentsuch as quenching and tempering is performed after the sleeve 16 isformed to thereby increase its strength.

As shown in FIG. 12(2), after the sleeve 16 is pressed into and fixed tothe nut socket shell portion 15 to obtain a fourth processed product E,as shown in FIG. 12(1) and FIG. 12(3), punching is performed to thefixing hole 16 a of the sleeve 16 from the outside of the nut socketshell portion 15 by using a punch bar 17, and as shown in FIG. 5 inparticular, the nut socket shell portion 15 is bulged to each of thefixing holes 16 a to form a nut socket portion 18, which is set as afifth processed product F. Next, as shown in FIG. 12(4), a handleportion is bent to form a bent portion 19, and a pierced hole 2 a isprovided by a press machine and a plated finish is performed, and then afinished product G is made. Note that an angle of the bent portion 19can be selected arbitrarily.

Further, an order in which the pierced hole 2 a is provided is notlimited. It is arbitrary that the pierced hole 2 a is not provided at alater step of the manufacturing process as described above but it isprovided at a different and earlier process. This pierced hole 2 a, asshown in FIG. 13( a) and FIG. 13( b), is to be used when a single-endedL-shaped wheel nut wrench 20 is used as a rotary handle to a rotaryshaft 21 of a vehicle jack. As shown in FIG. 13( b) in particular, whena size of the pierced hole 2 a is changed by making an entry 2 b of thispierced hole 2 a large and making an exit 2 c thereof small, in the casewhen a tip 21 a of the rotary shaft 21 is tapered, there is an advantagethat the tapered tip can be fit into the pierced hole 2 a without anytrouble because a handle portion 2 is tube shaped and a predeterminedinterval is provided between the entry 2 b and the exit 2 c. However, ashape of the pierced hole 2 a is according to a shape of the rotaryshaft 21 to be inserted, and it is not limited to the above in thisembodiment.

Note that in the above explanation, the case when the present inventionis applied to the single-ended L-shaped wheel nut wrench is explained,but as described above, it goes without saying that the presentinvention can also be applied to an open-ended type wheel nut wrench anda single-ended T-shaped wheel nut wrench besides the above.

The present invention is constituted as above, and thus it is tubeshaped and strong against torsional deformation, and can be manufacturedinexpensively. Accordingly, the present invention has a possibility tobe widely used as a manufacturing process of a wheel nut wrench forvehicles in particular.

1. A manufacturing process of a wheel nut wrench comprising the stepsof: providing a tube-shaped steel tube; forming a nut socket shellportion having a cross section of a hexagonal shape at an end portion ofthe steel tube by cold pressing; pressing a sleeve made by a belt-shapedsteel plate being bent and having a cross section of a hexagonal shapeinto the nut socket shell portion; and unifying a nut socket portionwith the sleeve by plastic deforming.
 2. The manufacturing process ofthe wheel nut wrench according to claim 1, wherein a shape of the nutsocket shell portion is constituted in a manner that outer and innerperipheries thereof are both formed in a hexagonal shape.
 3. Themanufacturing process of the wheel nut wrench according to claim 1,wherein a heat treatment is performed for the sleeve.